How is the efficiency of the primary filter measured?

They are often made of man-made fiber filter material, using a strong, moisture-proof cardboard frame as the outer frame, which will not deform, break or twist under normal operating conditions, and the filter material is fixed diagonally at the front and rear of the frame, with the filter material and the frame closely bonded to the outer frame to prevent air leakage, It is mainly used as primary filtration for multi-stage filtration systems.

Clean room primary filter is mainly used for filtering dust particles of 5μm and above particle size filtration efficiency is measured by the weighting method, filter materials are non-woven, nylon mesh, aluminum wave mesh, stainless steel mesh, etc., non-woven filter media out of the air surface after light finishing treatment, to prevent non-woven fibers from breaking and flying apart causing secondary pollution, next talk about the weighting method, the weighting method is generally used to measure the low efficiency of the central air conditioning system as a pre-filter Filters, i.e. primary filters:

The relevant standards for the gravimetric test are ANSI/ASHRAE 52.1 - 1992, EN 779 - 1993, and GB 12218 - 1989.

The filtration efficiency of the primary filter is the ratio of the amount of captured dust to the original air dust content. The filtration efficiency of the primary filter is equal to the ratio of the downstream air dust content to the upstream air dust content, the filter is installed in a standard test wind tunnel and the dust is generated intermittently at the upwind end. The filter is installed in a standard test wind tunnel with intermittent dust generation at the upwind end.

At regular intervals, the weight of dust passing through the filter (the amount of dust collected on the filter) is measured to obtain the filtration efficiency of the filter by the weight of dust at that stage, the final weighted efficiency being the weighted average of the efficiencies at each test stage according to the amount of dust generated. The conditions for the termination of the weighting test are: the final resistance value agreed with the customer, or the final resistance value specified by the tester himself, or when the efficiency falls significantly, obviously, the final resistance value is different, the weighting efficiency value is different.

It is important to note that the weight test is destructive and cannot be used for daily product performance testing in the manufacturing plant.